nArudrO rudramarchayEt is usually quoted by the performers of mahanyAsa pUrvaka rudrAbhishEka ritual as an explanation for the anganyaasa karanyaasa portions of the ritual in which the performer does aavaahana (the supernatural process of bringing and filling the spirit into one's own self)  of rudra onto himself.

 

Similar anganyaasa karanyaasa portions form the early part of archanaa of many other dEvas. nAdevo devam arcayet is probably an extension of the statement nArudrO rudramarchayEt to the rituals other than rudrAbhiShEka.
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Prof.Nagaraj Paturi

Hyderabad-500044